This invention relates to the use of suitable fatty acid radical-containing glycerides as flow promoting agents in powdered acrylic paint formulations and to a method of coating with such formulations.
For many years, acrylic resin painting processes have employed organic solvent-type vehicles, and the various formulations and spraying techniques have been highly refined. The vehicle provides fluidity, permitting the applied paint droplets to flow into a smooth, continuous film before the vehicle is evaporated. The resultant finishes are of high quality in terms of both appearance and durability.
In view of problems inherent in the use of organic solvents, interest has shifted to dry paint formulations which can be electrostatically sprayed in powder form onto a substrate. A suitable powder coating would then be baked to fuse the layer of discrete particles and induce them to flow into a smooth, glossy surface. However, heretofore such solvent-free coatings have not been observed to flow upon fusion into the smooth, glossy coatings indicative of the prior art acrylic lacquer coatings. At the conclusion of the bake operation, powder coatings are still relatively rough and often display a characteristic "orange peel" appearance. The viscosity of fused prior art powder coatings in the bake operation is relatively high, particularly at low shear rates. The principal flow-inducing force acting on the fused powder coating is surface tension which has proved ineffective in leveling prior art powder coating formulations.